In recent years, the use of light-emitting diodes (LEDs) in development of light fixtures for various common lighting purposes has increased, and this trend has accelerated as advances have been made in the field. Indeed, lighting applications which previously had typically been served by fixtures using what are known as high-intensity discharge (HID) lamps are now being served by LED light fixtures. Such lighting applications include, among a good many others, roadway lighting, factory lighting, parking lot lighting, and commercial building lighting.
In many of such products, achieving high levels of illumination over large areas with specific light-distribution requirements is particularly important. And in such situations it is desirable to minimize the use of large complex reflectors and/or varying orientations of multiple light sources to achieve desired illumination patterns.
Lighting fixtures using LEDs as light sources for various applications present particularly challenging problems. Heat dissipation is one particular problem. To ensure LED longevity and excellent long-term light-output performance, it is important that heat transfer away from the LEDs be facilitated in order to minimize thermal damage which may occur to LEDs during operation. Another problem, particularly when fixture mounting locations vary, is keeping LEDs protected from water, especially in outdoor locations. Dealing with these sorts of performance-related problems may sometimes be particularly difficult and involve various subtleties. In the present invention, long and involved trial-and-error development efforts led to performance breakthroughs.
In short, there is a significant need in the lighting industry for improved lighting fixtures using LEDs—fixtures that address problems associated with heat dissipation and appropriate protection of LEDs and which are adaptable for a wide variety of mountings and situations. Furthermore, there is a need for an improved LED-based lighting fixtures with high light-output performance and that are easy and cost-effective to manufacture.